Cardiovascular and bleeding outcomes in a population-based cohort of patients with chronic immune thrombocytopenia

Abstract

Essentials Immune thrombocytopenia (ITP) is an autoimmune disorder characterized by low platelet count. We conducted a cohort study of 3 584 chronic ITP patients from the Nordic countries. Cardiovascular events occurred across all platelet count levels. Cardiovascular or bleeding events were strong prognostic factors for all-cause mortality. Background Among patients with chronic immune thrombocytopenia (cITP), little is known regarding risk factors for cardiovascular and bleeding outcomes and how these events influence mortality. Objectives We examined the rate of cardiovascular events and bleeding requiring a hospital contact according to platelet count levels, as well as the prognostic impact of these events on all-cause mortality in adult patients with cITP. Methods We identified all cITP patients registered in the Nordic Country Patient Registry for Romiplostim during 1996 to 2015. Absolute risks and hazard ratios across platelet count levels based on Cox regression analysis were computed, adjusting for age, sex, prevalent/incident cITP, smoking, and comorbidities. We also compared all-cause mortality rates in cITP patients with and without cardiovascular and bleeding events. Results Among 3 584 cITP patients, 1-year risks were 1.9% for arterial cardiovascular events, 1.2% for venous thromboembolism, and 7.5% for bleeding. Rates of cardiovascular events were similar across platelet counts. Patients with platelet counts <50 × 10⁹ /L had >2-fold higher rates of bleeding than patients with normal platelet counts. These associations were unchanged in time-varying analyses that considered changes in platelet counts during follow-up. Occurrences of cardiovascular and bleeding events were associated with 4-fold to 5-fold increases in 1-year mortality. Conclusions Among patients with cITP, the 1-year risks of cardiovascular events were 1% to 2%, while nearly 8% experienced a bleeding event within 1 year. Cardiovascular events occurred across all platelet levels, while low platelet counts were associated with increased hazards of bleeding. Cardiovascular and bleeding events were strong prognostic factors for mortality.

Keywords: bleeding; chronic ITP; epidemiology; mortality; stroke, myocardial infarction; venous thromboembolism.